Many surgical procedures require two or more parts of a sternum to be reapproximated, or fixed together, such as sternal reconstruction and repair of sternal trauma. In addition, various types of surgical procedures are currently performed to investigate, diagnose, and treat diseases involving tissues or organs located in a patient's thoracic cavity, such as the heart and lungs. These procedures typically require a partial or median sternotomy to gain access to the patient's thoracic cavity. A partial or median sternotomy is a procedure by which a saw or other appropriate cutting instrument is used to make a midline, longitudinal incision along a portion or the entire axial length of the patient's sternum, allowing two opposing sternal halves to be separated laterally. A large opening into the thoracic cavity is thus created, through which a surgeon may directly visualize and operate upon the heart and other thoracic organs, vessels, or tissues. Following the surgical procedure within the thoracic cavity, the two severed sternal halves must be reapproximated.
Sternum fixation has traditionally been performed using stainless steel wires that are wrapped around or through the sternal halves and then twisted together, so as to compress the two halves together. Other methods of sternum fixation include the use of band or strap assemblies. Such assemblies typically include a locking mechanism, which secures a strap in a closed looped configuration around the sternum halves. While utilization of steel wires and strap assemblies have been widely accepted for sternum fixation, these devices present a number of disadvantages. For example, steel wires are susceptible to breakage, are difficult to maneuver and place around the sternum, and often have sharp ends that can pierce through the surgeon's gloves or fingers. Steel wire and band assemblies also provide insufficient or non-uniform clamping force on the sternal halves, thus resulting in sternal nonunion. The steel wire and band assemblies also provide insufficient clamping forces in all three planar directions, thus leading to healing problems caused by unwanted bone movements leading to raking and rubbing of the surrounding tissue or bone.
Several other techniques of sternal fixation have been developed for reapproximating the sternal halves. One technique uses plates that are located on both sternal halves across the sternotomy and are fixed thereto by means of screws through the bone on either side of the sternotomy. This technique, however, is not optimal because it requires direct fixation of the plates to the bone with screws, making reentry into the thoracic cavity through the sternotomy extremely difficult in case of a medical emergency.
Another technique uses a sternal clamp having a pair of opposed generally J-shaped clamp members which are laterally adjustable relative to one another but can be rigidly joined with a set of machine screws. Similar to the use of plates, discussed above, this technique does not provide quick access to the organs and/or tissues within the patient's thoracic cavity.
Yet another fixation device comprises a pair of hook-shaped clamps that slide together and lock in position with respect to one another using a ratchet assembly. The ratchet assembly provides quickened accesses to the thoracic cavity, but is cumbersome to use and is limited to the hook-shaped clamp members disclosed.
Therefore, it is desirable to provide a sternum fixation device that stabilizes the sternum in all three planar directions, has a fast and easy to use quick-release feature, and works in several different configurations.